Bottom Line:
We found that both of the tested non-CpG ODN exerted significant immunomodulatory effects on early T cell and on late B cell activation events.Importantly, a synergism between non-CpG effects and T cell help acting on B cells was observed, resulting in enhanced IgG production following cognate T cell-B cell interactions.We propose that non-CpG ODN may perform as better adjuvants when a strong antigen-independent immune activation, elicited by CpG ODNs, is undesirable.

ABSTRACTNatural and synthetic nucleic acids are known to exert immunomodulatory properties. Notably, nucleic acids are known to modulate immune function via several different pathways and various cell types, necessitating a complex interpretation of their effects. In this study we set out to compare the effects of a CpG motif containing oligodeoxynucleotide (ODN) with those of a control and an inhibitory non-CpG ODN during cognate B cell-T cell interactions. We employed an antigen presentation system using splenocytes from TCR transgenic DO11.10 mice and the ovalbumin peptide recognized by the TCR as model antigen. We followed early activation events by measuring CD69 expression, late activation by MHC class II expression, cell division and antibody production of switched, and nonswitched isotypes. We found that both of the tested non-CpG ODN exerted significant immunomodulatory effects on early T cell and on late B cell activation events. Importantly, a synergism between non-CpG effects and T cell help acting on B cells was observed, resulting in enhanced IgG production following cognate T cell-B cell interactions. We propose that non-CpG ODN may perform as better adjuvants when a strong antigen-independent immune activation, elicited by CpG ODNs, is undesirable.

fig3: Enhancement of ASC formation by non-CpG ODN. Cells were incubated with the different combinations of ODNs and OVA as indicated; then after 4 days the cultures were transferred onto nitrocellulose-covered slides coated with light chain capture antibodies. After 10 hours of incubation, slides were washed and IgM (a) and IgG (b) spots produced by ASCs were detected using labeled antibodies and a fluorescent scanner. A representative fluorescent spot experiment is shown in (c). Statistical significance was calculated using two-tailed permutation test. Treatment pairs with significant differences (P < 0.05) are indicated by connecting brackets; thin lines for within OVA treatment group comparisons and thick lines for OVA treatment effects. ASC: antibody secreting cell.

Mentions:
The number of both IgM and IgG-producing ASCs was higher in the presence of Inhibitor or Control ODNs, as well as in the presence of CpG ODN (Figures 3(a) and 3(b)). This was true in both absence and presence of OVA; that is when T cell help was provided for B cells, implying that not only CpG but also non-CpG ODN promoted differentiation of B cells into ASC. Importantly, pairwise comparisons of non-CpG but not CpG treatments with and without OVA showed additive effects (Figures 3(a) and 3(b)).

fig3: Enhancement of ASC formation by non-CpG ODN. Cells were incubated with the different combinations of ODNs and OVA as indicated; then after 4 days the cultures were transferred onto nitrocellulose-covered slides coated with light chain capture antibodies. After 10 hours of incubation, slides were washed and IgM (a) and IgG (b) spots produced by ASCs were detected using labeled antibodies and a fluorescent scanner. A representative fluorescent spot experiment is shown in (c). Statistical significance was calculated using two-tailed permutation test. Treatment pairs with significant differences (P < 0.05) are indicated by connecting brackets; thin lines for within OVA treatment group comparisons and thick lines for OVA treatment effects. ASC: antibody secreting cell.

Mentions:
The number of both IgM and IgG-producing ASCs was higher in the presence of Inhibitor or Control ODNs, as well as in the presence of CpG ODN (Figures 3(a) and 3(b)). This was true in both absence and presence of OVA; that is when T cell help was provided for B cells, implying that not only CpG but also non-CpG ODN promoted differentiation of B cells into ASC. Importantly, pairwise comparisons of non-CpG but not CpG treatments with and without OVA showed additive effects (Figures 3(a) and 3(b)).

Bottom Line:
We found that both of the tested non-CpG ODN exerted significant immunomodulatory effects on early T cell and on late B cell activation events.Importantly, a synergism between non-CpG effects and T cell help acting on B cells was observed, resulting in enhanced IgG production following cognate T cell-B cell interactions.We propose that non-CpG ODN may perform as better adjuvants when a strong antigen-independent immune activation, elicited by CpG ODNs, is undesirable.

ABSTRACTNatural and synthetic nucleic acids are known to exert immunomodulatory properties. Notably, nucleic acids are known to modulate immune function via several different pathways and various cell types, necessitating a complex interpretation of their effects. In this study we set out to compare the effects of a CpG motif containing oligodeoxynucleotide (ODN) with those of a control and an inhibitory non-CpG ODN during cognate B cell-T cell interactions. We employed an antigen presentation system using splenocytes from TCR transgenic DO11.10 mice and the ovalbumin peptide recognized by the TCR as model antigen. We followed early activation events by measuring CD69 expression, late activation by MHC class II expression, cell division and antibody production of switched, and nonswitched isotypes. We found that both of the tested non-CpG ODN exerted significant immunomodulatory effects on early T cell and on late B cell activation events. Importantly, a synergism between non-CpG effects and T cell help acting on B cells was observed, resulting in enhanced IgG production following cognate T cell-B cell interactions. We propose that non-CpG ODN may perform as better adjuvants when a strong antigen-independent immune activation, elicited by CpG ODNs, is undesirable.